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Program and Abstracts: The Seventeenth Conference of the International Society for Environmental Epidemiology (ISEE): Abstracts

EFFECT OF DDT ON WILDLIFE

Anderson, D W.

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ISEE-456

DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) has been around as an organochlorine (OC) insecticide since 1939, after which it literally won WWII for the allies. In fact, Herman Müller received a Nobel Peace Prize for his work in introducing DDT to the world as an insecticide.

After its early successes in improving human health, then helping to control pests, DDT and its chlorinated relatives were widely considered “miracle chemicals.” The “chemical revolution” had begun and continues today, earlier leading to a large variety of organochlorine insecticides, used mainly in the 2-3 decades following the discovery of DDT. Given the extensive widespread and heavy use of DDT in the “early days”, coupled with its catabolic characteristics into a highly recalcitrant molecule, DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene), along with a strong tendency for it to bio-accumulate, and that along with a persistent lack of ecological insight or appreciation by human society, led to problems almost nobody had imagined.

Many of the serious ecological ramifications of DDT-use resulted in massive and widespread population declines of many high trophic level species of birds over large geographic areas. DDT, through DDE, had become a “chemical of extinction.” The major physiological effect on individuals, ultimately manifested by poor reproduction and rapid population decline, occurred through eggshell thinning, caused by numerous physiological mechanisms, many of which have been demonstrated in the laboratory as well as in the field.

Once DDT use subsided, however, populations began to recover as DDE residues further degraded or otherwise became unavailable in food-webs (buried in sediments, etc.). Although DDE residues have declined in general and associated eggshell thinning has improved, significant DDE-induced eggshell thinning can still be shown in some populations of birds. From start to finish, this was all a 60+ year process, one person's lifetime (a 30-year state of ignorance and unforeseen damage + another 30 years of recovery, which continues even today).

The question we must now address, however, is whether we want to risk these and perhaps additional unknown ramifications of OC use again, as new or unforeseen human health problems emerge. The lessons of DDT should not be repeated, regardless of the short-term benefits that might be imagined. The same 60 years have also been a period of tremendous human innovation, and there is no reason to believe that this ingenuity cannot find a more ecologically-compatible solution to problems imagined as previously solvable by DDT.

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